Welcome to the Climate and Water Outlook for spring 2016.
The negative Indian Ocean Dipole, which brought plenty of winter rainfall, has eased back
from its record July values; and La Niña still hasn't locked in.
This means the chance of getting above-average spring rains has reduced in the southeast.
But first, let's look at recent conditions.
Winter rainfall has been well above average for large parts of Australia, with some places
receiving more than twice their average rainfall.
Southwest Western Australia is one of the few areas to have had lower-than-average rainfall
this winter.
However, in many places soils are wet, streams are flowing, and dams are filling.
Lower-layer soil moisture is now well above average across much of Australia, increasing
the risk of spring floods, but also priming the landscape for good pasture and crop growth
as the weather warms.
Key cropping regions are already looking greener than average, thanks to good autumn rains
in WA, and good rains in both autumn and winter elsewhere.
In southern New South Wales, the lower Darling River has started flowing for the first time
in a year.
Storages continue to rise as water flows through the landscape.
Murray–Darling Basin storages are 12 per cent higher than at this time last year.
Other regions have also seen large rises.
Daytime temperatures were unusually warm in far northern Australia.
Kalumburu in WA broke the national record for the hottest July day, reaching 38.3°C
on the 24th.
In contrast, southwest WA had its coolest winter since 1990.
Globally, July was the hottest month ever recorded, beating the old record set last year.
So what's driving Australia’s climate right now?
The Indian Ocean Dipole, or IOD, peaked in July at its strongest negative value in at
least 50 years.
A negative IOD typically increases the number of weather systems crossing southern Australia,
bringing tropical moisture southwards, boosting winter rainfall.
However, the negative IOD weakened in August, and models predict it will slowly ease back
to neutral levels by November.
This means the IOD may not influence Australian rainfall in spring as strongly as it did over
winter.
In the tropical Pacific, ocean temperatures are likely to cool further, but possibly not
enough to push us into La Niña.
Our ENSO Outlook remains at La Niña WATCH.
If La Niña does develop, it is likely to be short and weak.
Despite this, we may still see La Niña-like impacts, such as increased rainfall in eastern
Australia, and an early onset to the rains in the north.
So what's the outlook for spring?
Above-average rainfall is likely across northern Australia.
Elsewhere, there is no strong push towards either a wetter or drier spring than usual.
Outlook accuracy is moderate at this time of year.
Our northern rainfall onset outlook shows an increased chance of early wet season rains
for northern Australia.
Turning now to the streamflow forecast, with catchments already wet, high streamflows are
forecast at 88 locations, with near-median flows likely at 27 locations and low flows
expected at only 16.
Accuracy for our streamflow forecast is high at this time of year.
The risk of flooding remains in some parts of Australia, after strong winter rains have
saturated the soils in many areas.
In terms of spring temperatures, days and nights are likely to be warmer than usual
across much of Australia, but frosts are still possible on calm and clear nights.
Accuracy for this outlook is moderate to high at this time of year.
So in summary, northern Australia is likely to receive above-average rainfall.
With soils already wet and high streamflows more likely, flood risk continues in parts
of Australia.
And temperatures are likely to be warmer than average.
For more details, go to our website at bom.gov.au/climate/ahead.
You can also get updates via Facebook and Twitter.
Our next video will be released on Thursday the 29th of September.
For the Bureau of Meteorology, I’m Robyn Duell.